By signing on to the war on Hollywood, the right has embraced another bad idea from the left.

“If liberals can get away with it, it must be all right,” is the latest conservative substitute for an original idea. At first, it was sexual McCarthyism. For years the left pushed political agendas into the private sphere, while conservatives looked on in paralytic awe.

Soon, Supreme Court nominees had to be careful what videos they rented, and 6-year-olds were being publicly shamed for sneaking illicit kisses from kindergarten mates. Eventually a liberal president caught his fly in an Oval Office portal, and conservatives concluded they could dispatch him with ease.

Of course, it didn’t work out that way. They should have learned from the experience.

But apparently they haven’t. Now it’s the left’s newest crusade against “media pollution” that the right can’t wait to join. For some time now, conservatives have watched as the left conducted mind experiments on American campuses, regulated speech and punished ideas that were politically incorrect.

Conservatives fought a rear-guard battle against these academic commissars, managing to achieve a modicum of success. Most of the speech codes were shredded, and the censors were forced to beat a partial retreat. But the political mind-set has remained and continues to rule the academic world.

As a result, no institution in American life is as intellectually monolithic as a university faculty. Not surprisingly academic “scholars” of the left have provided an elaborate structure of theory, and underpinned it with “scientific” research, to justify the resurgence of censorship in American life.

On the right, religious conservatives have been traditionally attracted to this seductive fix for sinful humanity. But now even the secular minds of the conservative intelligentsia are climbing on board.

It is true that even while they were being banished from American classrooms, a cadre of conservative intellectuals was already making the case for public censorship.

Arguing that artistic expressions were not covered by the Bill of Rights, they made government-funded pornographic art the first target of their complaint, but suggested that even non-government licentiousness was a proper government concern.

When liberals like Bill Clinton and Tipper Gore showed that a bluenose crusade against the entertainment industry might actually become a popular cause, these conservatives were eager to sign on.

Now both groups have come together behind an “Appeal to Hollywood,” complaining about the moral pollution of the popular culture. Mindful of Americans’ quaint attachment to their First Amendment privileges, the “appeal” only asks the entertainment industry to “take modest steps of self-restraint” to decrease the levels of sex and violence perceived in its products.

The “appeal” was signed by 67 prominent public figures, members of a new popular front that joins such unlikely couples as Bill Bennett and Mario Cuomo, Jimmy Carter and Lynne Cheney.

But the “Appeal to Hollywood” is only part of a growing and disturbing trend on both ends of the political spectrum whose efforts are weakening the bulwarks that protect our First Amendment freedoms.

The federal government and the Congress have already put the entertainment industry on the block and slated it for investigation and legislation (soon to be followed, if precedent is a guide, by class action lawsuits).

It is a consciously designed parallel to the assault on tobacco and gun manufacturers. If one focuses on the fact that entertainment products are ideas, images and fantasies, the mere linking of these three industries should send shivers up the national spine.

The steady advance of this juggernaut of repression, however, was apparently not fast enough for the editors of the Weekly Standard. The August 23 issue of the leading intellectual organ of neo-conservatism is devoted to “The Case For Censorship,” the title of a feature article by a political scientist named David Lowenthal.